According to 82games, Porter played both SF and PF, but mostly SF (73% of his minutes). He was mostly on the court with either Millsap or Gordon. But he is 6'-10". I would rather have him at PF/Swing on the Celtics than Tatum.
Not sure if Denver would let him go and even if they did, who we could sign or trade for him. I think he would be a great fit though.